my older siblings are more abusive than my parents

I'm 16 female. I dont live with my family, I live with my grandmother. but I still have to keep in touch with them (They drop me off at school. my school is so far away from our home so bus cannot come). my sis is 31/F, my brother is 30/M. they still live with my parents, (idk why) and my parents dont see it as a problem.

my sis is always verbally abuse me. She is forcibly taking something I do not want to give her, and is forcibly eating my food. She calls me a selfish ungrateful person. always yelling at me when I dont do anything. I wanna study language at the university but she doesnt want it, always force me to not study language. I dont live with them but she still verbally abuse me. when I talk to my mother, she calls me ungrateful bc some people dont have a family. one day me and my sis had a fight then my father beat me up(I haven't talked to my father since that day) then I apologized my sis for the fight. she does good things(for example buys me something that I need, or pick me up from the school, or make my bday cake) but still act like she's my personal bully. I was going to call the police after the fight with my father, but my sister stopped me and then got angry with me.

I dont talk with my brother if it's not necessary. he beat me up more than my parents did. I still anxious when I with him. Idk what changed him.In the fight I just told you about with my father, my brother said to my father, "I'll beat her up, you calm down" (thank God he didn't).When I received death threats from my ex, I couldn't tell him because I was afraid he would beat me because I dated with someone. he interferes with my clothes. When I was a child he was my favotire family member. we have a good memories. my mom says my brother was so excited about me before I was born, and took care of me when I was a baby. it feels like a believing a lie. I dont wanna believe it's real. when I was 10-11 he choked me up then everything is changed, he wasnt the lovely protective older brother anymore he was like a hitman.

what I'm gonna do? I dont live with them but they still abuses me :/